#include <osg/Node>
#include <osg/Group>
#include <osg/Geode>
#include <osg/Geometry>
#include <osg/Texture2D>
#include <osgDB/ReadFile> 
#include <osgViewer/Viewer>
#include <osg/PositionAttitudeTransform>
#include <osgGA/TrackballManipulator>
int main()
{
    osgViewer::Viewer viewer;
    osg::Group* root = new osg::Group();
    osg::Geode* pyramidGeode = new osg::Geode();
    osg::Geometry* pyramidGeometry = new osg::Geometry();

    //Associate the pyramid geometry with the pyramid geode
    //   Add the pyramid geode to the root node of the scene graph.

    pyramidGeode->addDrawable(pyramidGeometry);
    root->addChild(pyramidGeode);

    //Declare an array of vertices. Each vertex will be represented by
    //a triple -- an instances of the vec3 class. An instance of
    //osg::Vec3Array can be used to store these triples. Since
    //osg::Vec3Array is derived from the STL vector class, we can use the
    //push_back method to add array elements. Push back adds elements to
    //the end of the vector, thus the index of first element entered is
    //zero, the second entries index is 1, etc.
    //Using a right-handed coordinate system with 'z' up, array
    //elements zero..four below represent the 5 points required to create
    //a simple pyramid.

    osg::Vec3Array* pyramidVertices = new osg::Vec3Array;
    pyramidVertices->push_back( osg::Vec3( 0, 0, 0) ); // front left
    pyramidVertices->push_back( osg::Vec3(10, 0, 0) ); // front right
    pyramidVertices->push_back( osg::Vec3(10,10, 0) ); // back right
    pyramidVertices->push_back( osg::Vec3( 0,10, 0) ); // back left
    pyramidVertices->push_back( osg::Vec3( 5, 5,10) ); // peak

    //Associate this set of vertices with the geometry associated with the
    //geode we added to the scene.

    pyramidGeometry->setVertexArray( pyramidVertices );

    //Next, create a primitive set and add it to the pyramid geometry.
    //Use the first four points of the pyramid to define the base using an
    //instance of the DrawElementsUint class. Again this class is derived
    //from the STL vector, so the push_back method will add elements in
    //sequential order. To ensure proper backface cullling, vertices
    //should be specified in counterclockwise order. The arguments for the
    //constructor are the enumerated type for the primitive
    //(same as the OpenGL primitive enumerated types), and the index in
    //the vertex array to start from.

    osg::DrawElementsUInt* pyramidBase =
        new osg::DrawElementsUInt(osg::PrimitiveSet::QUADS, 0);
    pyramidBase->push_back(3);
    pyramidBase->push_back(2);
    pyramidBase->push_back(1);
    pyramidBase->push_back(0);
    pyramidGeometry->addPrimitiveSet(pyramidBase);

    //Repeat the same for each of the four sides. Again, vertices are
    //specified in counter-clockwise order.

    osg::DrawElementsUInt* pyramidFaceOne =
        new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceOne->push_back(0);
    pyramidFaceOne->push_back(1);
    pyramidFaceOne->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceOne);

    osg::DrawElementsUInt* pyramidFaceTwo =
        new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceTwo->push_back(1);
    pyramidFaceTwo->push_back(2);
    pyramidFaceTwo->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceTwo);

    osg::DrawElementsUInt* pyramidFaceThree =
        new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceThree->push_back(2);
    pyramidFaceThree->push_back(3);
    pyramidFaceThree->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceThree);

    osg::DrawElementsUInt* pyramidFaceFour =
        new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceFour->push_back(3);
    pyramidFaceFour->push_back(0);
    pyramidFaceFour->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceFour);

    //Declare and load an array of Vec4 elements to store colors.

    osg::Vec4Array* colors = new osg::Vec4Array;
    colors->push_back(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f) ); //index 0 red
    colors->push_back(osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f) ); //index 1 green
    colors->push_back(osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f) ); //index 2 blue
    colors->push_back(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f) ); //index 3 white
    colors->push_back(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f) ); //index 4 red

    //The next step is to associate the array of colors with the geometry,
    //assign the color indices created above to the geometry and set the
    //binding mode to _PER_VERTEX.

    pyramidGeometry->setColorArray(colors);
    pyramidGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);

    //Now that we have created a geometry node and added it to the scene
    //we can reuse this geometry. For example, if we wanted to put a
    //second pyramid 15 units to the right of the first one, we could add
    //this geode as the child of a transform node in our scene graph.

    // Declare and initialize a transform node.
    osg::PositionAttitudeTransform* pyramidTwoXForm =
        new osg::PositionAttitudeTransform();

    // Use the 'addChild' method of the osg::Group class to
    // add the transform as a child of the root node and the
    // pyramid node as a child of the transform.

    root->addChild(pyramidTwoXForm);
    pyramidTwoXForm->addChild(pyramidGeode);

    // Declare and initialize a Vec3 instance to change the
    // position of the model in the scene

    osg::Vec3 pyramidTwoPosition(15,0,0);
    pyramidTwoXForm->setPosition( pyramidTwoPosition );

    // switch off lighting as we haven't assigned any normals.
    root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);

    //The final step is to set up and enter a simulation loop.

    viewer.setSceneData( root );
    //viewer.run();

    viewer.setCameraManipulator(new osgGA::TrackballManipulator());
    viewer.realize();

    while( !viewer.done() )
    {
        viewer.frame();
    }

    return 0;
}
